Which nation held the edge in the arms race until the late 1960s?

The United States held the edge in the arms race until the late 1960s, primarily due to its significant advancements in nuclear weapons technology and delivery systems. The U.S. developed a substantial stockpile of nuclear warheads and intercontinental ballistic missiles (ICBMs), which provided a strategic advantage. However, this dynamic began to shift as the Soviet Union made significant strides in its own nuclear capabilities, culminating in the development of their own ICBMs and a growing arsenal, leading to a more balanced nuclear standoff.